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British Standard Whitworth Thread (BSW)

The Whitworth thread was the world's first national screw thread standard,devised and specified by Joseph Whitworth in 1841. Until then, the only standardization was what little had been done by individual people and companies, with some companies' in-house standards spreading a bit within their industries.

The Whitworth thread system was later to be adopted as a British Standard to become British Standard Whitworth.

With the adoption of BSW by British railway lines, many of which had previously used their own standard both for threads and for bolt head and nut profiles, and improving manufacturing techniques, it came to dominate British manufacturing.

In the USA, BSW was replaced when steel bolts replaced iron, but was still being used for some aluminium parts as late as the 1960s and 1970s when metric based standards replaced the Imperial ones.

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